Process for heating decomposable materials



Sept. 1, 1931. J. R. scHowaEkc; 1,821,326

PROCESS FOR HEATING DECOMPOSABLE MATERIALS Filed June 11, 1927 Q//II1II/I//A7111/11/1/1/11111/0 114w. 00 a 1 s,

v 6 JACKSON Rficuovmuwa. anwntoz Patented Sept. 1, 1931 UNITED STATESPATENT OFFICE I JACKSON R. SCHONIBERG, OF WESTFIELD, NEW JERSEY,ASSIGNORJIO STANIJARD OIL DEVELOPMENT COMPANY, A. CORPORATION QEDELAWARE vPROCESS FOR HEATING DECOMPOSAIBLE MATERIALS Application filedJune 11,

The present invention relates to the art of heating fluids by combustiongases and more specifically comprises an eflicient method for, thedistribution of heat in furnaces to prevent local over-heating and atthe same time to use fuel economically. M' method and apparatus thereforwill be fu ly understood from the following descripton and the attacheddrawings referred to in the same.

In the heating of fluids which are sensitive to excessive temperatures,such as oils and the like, there has been great difliculty in obtainingefiicient combustion. If the excess air, as indicated by flue gasanalysis, is kept low, the temperature in the zone of combustion will behigh and radiation from the flames and the inner walls of the furnace isoften injurious to the heating surface and the material being heated. Inoil heating equipment this is especially troublesome since overheatingof the oil causes a deposition of coky material on the heating surfaceand the still J may be seriously damaged.

The condition above described is generally met by allowing a largeexcess of air to enter the combustion zone with the result that thetemperature therein is lowered to a point at which the radiation is notsufiiciently intense to cause over-heating, but fuel efliciency suffersin consequence as will be well understood.

It is a well known fact that certain gases, notably steam and carbondioxide, are semiopaque to heat rays. The expression semiopaque meansthat a certaln proportion of heat passing by radiation into a layer ofgas is absorbed by the gas itself, depending on the thickness of thelayer and the nature of the gas, so that only a certain fraction of theradiation passes through and leaves the as layer. My invention consistsin maintalmng a layer or bank of such a semi-opaque gas between theradiating elements and the stall surface. A part of the heat passesdirectly through the gas layer and is absorbed by the metal surfacewhile the remainder is absorbed by the gas layer. As the gas becomesheated it may be drawn off and utilized in another part of the furnace.

Referring to the drawings, Fig. I is a ver- 1927. Serial No. 198,134.

tical elevation in section of a pipe still heating coil constructedaccordingto my invention and,

Fig. II shows a shell type oil still, adapted for operationof myprocess.

the furnace by the stack 7 which is fitted with damper 8.

In sectionl the heating surface 9, in the form of parallel tubes, isplaced well above the furnace floor and the height above the burnerlevel is suflicient so that a bank or layer of a semi-opaque gas may bemaintained between the burner level and the heating surface. Thesemi-opaque gas may be admitted by pipes 10 above burners 6. The top ofthe combustion chamber is sealed so that the only escape for combustiongas is through holes 4, which are close to the floor level, preferablyin alignment with the burners 6, and by this means the layer ofsemiopaque gas may be maintained with little tendency for hot gas fromthe flames sweeping up around the tubes 9. Additional heating surface 11is distributed throughout the section 2 in order that the temperature ofthe flue gas may be reduced to an economical degree before discharge tothe stack. The semi-opaque gas is drawn from any convenient source notshown in Fig. 1 and, after discharge from the fire box. It is mixed withthe combustion gases and flows through section 2. The oil is pumpedfirst through the convection section where it is preheated and throughthe combustion section as indicated by the arrows, or in any othersuitable manner, and is finally discharged to a vaporizing drum or towernot shown in Fig. 1.

In Fig. II my invention is applied to a crude or rerun still of theshell type. As in Fig. I, the character 1 designates the combustionchamber and numeral 2 again refers to the convection chamber. In thiscase, however, the combustion chamber consists of a number of fluesextending from end to end of the still. The other elements are numberedas in Fig. I. The shell 9' is protected by the semi-opaque gas admittedby line 10 above burners 6. A fan or blower 13 draws flue gas,containing steam and CO from flue 12 and for use as a part of thatmakingup the layer injected at 10. The other part of the flue gas passes fromflue 12 into stack 7 The other elements of the still such as chargingline, vapor line and tar draw-off are indicated by 13, 14 and 15respectively.

In the operation of my process the semi opaque gas is interposed as athick bank or layer between the still surface and those elements fromwhich the intensity of radiation is high. The thickness of the gas layerand the nature of the gas determine the quantity of heat absorbed in thecombustion section and regulation of the heat absorption may bemaintained by control of the flow of interposed gas and by itscomposition. It is important to keep the layer of gas intact as well aspossible so that the construction of the back wall 3 should be asdescribed. It has been found that, when burning fuel with about20%excess air and heating oil to a temperature in excess of 750 F., a layerof from 1 to 3 ft. in thickness and containing about 11% CO and 1.2% H 0was sufficient to protect the tubes from over-heating.

While my invention has been described in reference to heating oil, itshould be understood that the process is applicable to the heating ofany fluid sensitive to over-heating. My invention is not to belimited-by any theory of the mechanism or by any example given in theway of illustration. I wish to be limited only by the following claims,in which I claim all novelty inherent in my invention.

It is pointed out that the term source of radiation used in the claimsincludes both solid radiating surfaces such as highly heated furnacewalls and the layer of hot combustion gases.

I claim:

1. The method for protecting heat absorption surfaces of a still fromlocal overheating by radiation, comprising maintaining a relatively coollayer of a semi-opaque gas between such surfaces and the source ofradiation.

2. The method for protecting heat absorption surfaces of a still againstlocal over-heating due to radiation, comprising flowin a layer ofrelativel cool semi-opaque gas lae tween the heat absorption surfacesand the source of radiation.

3. The method for protecting heat absorption surfaces of an oil stillagainst local overheating due to excessive radiation comprising keepingthe flames and highly heated gas out of contact with the heating surfaceand tempering the intensity of radiation by interposing a layer ofrelatively cool, semiopaque gas between the source of radiation and theheating surface.

4;. The method for economically heating fluid sensitive to excessivetemperatures comprising burning fuel with relatively small excess of airin a radiation zone, interposing a layer of semi-0 aque gas between theflames and heating sur aces containing the fluid to be heated,withdrawing and mixing the gases from the radiation zone, passing thesame to a second heating zone and absorbing heat from said gasestherein.

5. A method according to claim 3, in which the semi-opaque gas is atleast one foot in thickness and contains substantially equal parts ofcarbon dioxide and water va or.

JACKSON R. SCHONB RG.

